Sintering of Ag paste for power devices die attach on Cu surfaces

The die-attach layer is one of the most critical elements for high-temperature power electronics applications. The increase in operating temperature requires new materials with higher melting points and suitable thermo-mechanical properties. Among the possible solutions, sintering of Ag pastes (nanoparticles, nanoflakes and particles near the nanosize range) is an interesting method, because it requires moderate (<;300°C) processing temperatures. These lower processing temperatures are suitable for implementation in mass manufacturing and the equipment for doing so are readily available. The aim of this write-up is to detail the qualification efforts being done on the Ag sinter solutions, in particular on copper (Cu) surfaces. The literature work will cover reliability and manufacturing concerns which are of primary interest to the general engineering community. These concerns must be addressed from several view points; design, processability and equipment. The outlook for implementation of this technology is bright and is in-line with the lead free initiative being addressed by the RoHS and WEEE directives for power devices.